4) the goal of ethics in research is to
a. ensure that no one is harmed
b. protect researchers from legal liability
c. identify what behavior is appropriate
d. ensure research sponsors fulfill their legal obligations

Ethics answer questions such as "what is appropriate" which is often interpreted as "how to achieve the well-being of everyone". However, this is not always possible: sometimes the choice is for example between testing on animals (which is bad) and testing on humans (also bad).

Thus the best answer is: C. identify what behavior is appropriate